MPP LV6548 Ground/Neutral Safety?
- Thread starter Tetawon
- Start date
This is what MPP told me:
I noticed there is voltage between ground and neutral on my LV6548 that has the old firmware. The new firmware LV6548 has 0V between ground and neutral.
I am updating the firmware and keeping the ground and neutrals separate. I could open it up and remove the screw, then bond in the panel, but I do not see the point because the ac output is in series. If they were in parallel, I would see more purpose to bonding in the panel. Well, I guess it depends on how you plan to use your units. I am not using the ac input.
I am updating the firmware and keeping the ground and neutrals separate. I could open it up and remove the screw, then bond in the panel, but I do not see the point because the ac output is in series. If they were in parallel, I would see more purpose to bonding in the panel. Well, I guess it depends on how you plan to use your units. I am not using the ac input.
Thanks for posting this! Apologies for starting a new thread about something already under discussion. I did search the forum for before posting, but missed this thread.Please see this thread on this issue. The issues Dan ran into had to do with an extra grounding leg. Please be very cautious modifying these units unless you thoroughly understand the purposes of bonding and earthing
AC side MPP LV6548 connections, critical load panel, wiring
Since posting that video, MPP Solar tech support (Andy Y) has advised me that the bond screw can be removed (and it is safe to do so) on the LV6548 inverter. In your video, around 5:32 lower left, there is what may be a bonding screw with a picture of a screw next to it. Is that the screw you...diysolarforum.com
Thanks Will! Can you share what the latest firmware revision is? Just now ordering 2 LV6548s an will have to check firmware first thing.
Lt.Dan
Solar Wizard
I have been trying to get firmware updates from MPP for a year! Both of my 2x inverters have 2 different firmware versions and I wanted to get them on the same page. Could you share that update?
I am receiving a laptop to do this today (did not want to run cables everywhere) and I have the adapter. Will try to get it to work and then report back here. Hopefully it is easy but I'll find out soon.
Zwy
Solar Wizard
Dan posted here about the issue. https://diysolarforum.com/threads/lv6548-grounding-issues.21531/
What seemed to have occurred (and you should look at his AC wiring video) was he was running the EGC from a junction box with other EGC's that were ganged on a busbar. He had created a loop somewhere and was getting the feedback from it.
The solution was running the EGC directly from the LV6548 to the main panel and the objectionable current disappeared.
Zwy
Solar Wizard
Correct, measuring voltage between a neutral and ground circuit is really pointless due to N-G bond. If voltage is present, there either is a poor connection or no N-G bond.
Current on ground is what needs to be measured.
Zwy
Solar Wizard
No, it is not shared. He has a transfer switch to direct power either from grid to his subpanel or from the inverters.
I suggest a 3 pole double throw to switch neutral also due to N-G bond. I do not recommend removal of a screw, that defeats the purpose and intent of bonding at the inverter under inverter power.
eabyrd
Solar Enthusiast
slow your roll partner. You're right about the 6548 not being UL Listed, but it is designed for the US market unlike the EU version Growatts. There is NOTHING that needs to be modified in the LV6548 to make it function perfectly well as either a 120 Volt Single Phase or a 240 Volt Split Phase power source. You simply need to wire it correctly making sure to Switch the Neutrals if you attach it to an AC source, and to NOT create a N-G Bond in the panel it services. If you're running multiple units you also need to make sure you do not create ground loops. As mentioned in the other thread I linked too MPP does NOT support the tying of an input neutral to an output neutral in any event, although their reasoning is suspect.. Yes the screw is removable, yes their "may" be a case for doing so in a splitphase environment, but it the unit is not "incompatible out of the box"
Zwy
Solar Wizard
Conforms to UL1741 under TUVus. You do know what TUVus is? https://www.eng-tips.com/viewthread.cfm?qid=266418
Are you trolling here or what?
eabyrd
Solar Enthusiast
Mr. P I too would be interested in knowing where to obtain the update though I'm not sure I'll apply it. Does MPP maintain a change-log of their firmware versions? The manual on page 26 describes a process for updating directly from a USB disk that is OTG compatible.
I would also enjoy a video on the upgrade process should you feel so inclined
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This video shows the screw...
Everyone "else" here has been awesome & helpful. Don't know why YOU ask if I'm a troll...smdh! Simply, I watched Will's video on the LV6548s (wherein he said these worked within the US out of the box...unlike the Growatts), did some checking here (I haven't posted since joining a year ago until this thread), and came across a YouTuber with issues. Since this is where the best info is that I've found for DIYers, I posted and asked. I have discovered an existing problem when passing thru utility, employing an NEC Required N/G bond from the Mains source. I reasonably "assumed" that a DIY Forum was the place to ASK QUESTIONS.
Regarding TUVs, no I haven't researched. I know it's US OSHA accepted and is considered equivalent to UL for a National Testing Lab. Not being a Code Compliance Engineer, researching further is a waste of my time.
So, if that's trolling to you, that's not my problem nor care!
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eabyrd
Solar Enthusiast
Simply run grounds to the input side to each inverter so each is properly earthed. Run a single ground from the AC output of 1 (and only 1) of your split-phase units to the panel they service. Just 1. Do not bond at the panel
Simple complete grounding, with no loops and no screws removed
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Thanks!
Timing is everything... Just so happens I have enough panels in place as of today to test this... Two LV 6548's, off-grid, wired for split phase 240. Everything is mounted and wired but hasn't been powered up yet. EG4-LL's in place too. Everything is in a shipping container [pics tomorrow] and the panel currently has N/G bonded. It sounds as is the simple fix is to remove the bond in the panel and let the inverters handle it. Not clear on
- A jumper wire between AC neutral IN and OUT
-Removing the screw from the 2nd LV6548.
or, if I leave the bond in the panel, remove both screws, and then run a "real" ground wire from the inverters? This is all a brand new setup, so I'm willing to do some testing.
- A jumper wire between AC neutral IN and OUT
-Removing the screw from the 2nd LV6548.
or, if I leave the bond in the panel, remove both screws, and then run a "real" ground wire from the inverters? This is all a brand new setup, so I'm willing to do some testing.
eabyrd
Solar Enthusiast
No - MPP does not support any connection between neutral in and out, not needed. These units require a dedicated loads panel. Do not use a pro-tran type transfer switch to feed them back into your main panel and share the neutrals. If you want to also bring AC directly to your loads panel you'll need an x-fer solution that switches neutral. See the thread I linked to earlier (and several others for that matter) for a nauseatingly repetitive discussion of this topic
Not required unless you insist on bonding in your dedicated loads panel. You say your loads panel is bonded, if so and if you have no AC input planned (AC Input would eventually come from another bonded source so that would be bad if you had a bond in your loads panel) then yes you should remove the screws from all units.
However look at this alternative with no bond in the load panel
